Diagrammer - importing resulting xml into gdb

I have a gdb already created in ArcGIS. I exported it to xml (schema only) and was able to open in Diagrammer. I then added a "relationship" between a table and a feature class, saved the xml, then attempted to import this xml into the original gdb. When I do this, the Source Name and the Target Name differ and the name conflicts are displayed in red. I don't know why they differ, I didn't change the names. The target names appear to have "_1" added to the end. So I can't import the new schema with the relationship.